I'm remodeling my hall bathroom, reusing the existing tub, and now that the greenboard is in, I need a tub surround. The opening is 31" deep and 60" wide, and 71.5" from tub sill to ceiling. The old walls are not perfectly plumb so I am not sure if 3-piece or 5-piece would be a better choice.

There are many to choose from, and online at the "big box stores", but also a very wide range of prices. The cheapest low-end ones are so flimsy I would not use them, but I don't want to spend $600+ either for a few pieces of plastic!